A manager at Localtel, a small telephone company, wants to determine how long service technicians need to perform a certain repair. In the past, an almost identical repair required 18.75 minutes, with a standard deviation of 0.2 minutes. Compute the sample size of times needing to be collected to ensure that they can be 90 percent confident of correctly estimating the repair time if the manager is willing to tolerate an error rate of 0.04.